1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
|
"""Copyright 2020 Ettus Research, a National Instruments Brand.
SPDX-License-Identifier: GPL-3.0-or-later
Access to GPIOs via libgpiod.
"""
import contextlib
import gpiod
@contextlib.contextmanager
def request_gpio(line, direction):
"""Context manager for a GPIO line.
:param line: The GPIO line to request
:param direction: The direction to requested for line
"""
line.request(consumer="mpm", type=direction)
try:
yield line
finally:
line.release()
class Gpio:
"""Class for accessing a named GPIO line via libgpiod.
The GPIO line is requested when the object is created.
"""
INPUT = gpiod.LINE_REQ_DIR_IN
OUTPUT = gpiod.LINE_REQ_DIR_OUT
FALLING_EDGE = gpiod.LINE_REQ_EV_FALLING_EDGE
def __init__(self, name, direction=INPUT, default_val=None):
"""Create new Gpio object.
:param name: The name of the GPIO line to access
:param direction: The direction to request for the GPIO line
:param default_val: The default value to assume for an output GPIO
"""
self._direction = direction
self._line = gpiod.find_line(name)
self._out_value = False
if self._line is None:
raise RuntimeError("failed to find gpio with name %s" % name)
if default_val is not None and direction == Gpio.OUTPUT:
self.set(default_val)
def get(self):
"""Read the value of this GPIO.
:return: The value of the GPIO line.
"""
if self._direction == self.OUTPUT:
return self._out_value
with request_gpio(self._line, self._direction) as gpio:
return bool(gpio.get_value())
def set(self, value):
"""Set the value of this GPIO.
:param value: The value to set the GPIO line to.
"""
with request_gpio(self._line, self._direction) as gpio:
gpio.set_value(int(value))
self._out_value = bool(value)
def event_wait(self, timeout=1):
"""Wait for an event to happen on this line.
:param timeout: The time to wait for an event in seconds.
The timeout has to be passed in full seconds as an int.
:return: True if an event happened, False if the wait timed out.
"""
with request_gpio(self._line, self._direction) as gpio:
return gpio.event_wait(sec=timeout)
|
